The present invention relates to methods and apparatus useful in the performance of ankle arthroscopy procedures and, more particularly, to a multifunctional system for providing ankle joint distraction in support of arthroscopic procedures.
In order to provide sufficient space for the arthroscope and various types of surgical instruments used in ankle arthroscopy, it is usually necessary to provide some form of joint distraction. The degree of distraction will vary depending on the nature of the procedure and the type and size of surgical instruments required. Various methods of non-invasive and invasive (skeletal) distraction have been utilized.
In general, non-invasive distraction methods are limited in the maximum amount of ankle joint distraction they can provide, but are basically less complex to utilize. Invasive distraction methods, on the other hand, can provide a much higher level of ankle joint distraction, but are inherently more complex to perform and, therefore, generally involve somewhat greater risk of complications. Nevertheless, invasive distraction may be the only appropriate means which can be utilized to accommodate the required arthroscopic procedure.
All non-invasive distraction techniques utilize some method of applying a distally directed force or load on the foot and ankle axially of the lower leg in opposition to an oppositely directed anchoring force applied through the leg. The distraction force may be applied by gravity, manually by a surgical assistant, or by some device providing a mechanical advantage. The distraction force may be controlled or relatively uncontrolled. Invasive skeletal distraction is typically applied by a mechanical distractor which is attached across the ankle joint to generally horizontally disposed pins in the lower tibia and heel bone. The distractor is threaded such that it is extensible against the resistance of the pinned connections to impose a separating tensile force on the ankle joint resulting in the desired distraction. The distractor typically includes a calibrated extensiometer to indicate the amount of distraction force. Bilateral distraction may also be utilized by extending the pins bicortically through the bones and attaching somewhat similar mechanical distractors to each side.
In accordance with prior art techniques, the surgeon would choose a distraction technique believed to be suitable prior to commencement of the surgery. The technique would either be one of several non-invasive methods or some variation on the basic invasive skeletal distraction method. Obviously, if adequate, one of the non-invasive techniques would be preferable to obviate the need for surgical pin placement and the possible complications attendant thereto. Unfortunately, the amount of distraction obtained is often not determinable until the arthroscopic procedure has been commenced and, if adequate distraction by non-invasive methods cannot be attained, the surgical procedure must often be terminated completely.
It would be desirable, therefore, to have an ankle distraction system which could utilize, as necessary, basic non-invasive techniques and, if necessary as the anthroscopic examination or surgical procedure evolves, the direct replacement of non-invasive techniques with a skeletal distraction method or methods to provide a greater amount of distraction. It would also be desirable to have a system in which the preliminary non-invasive distraction could be better monitored and controlled, both in terms of the distraction force applied to the joint and the position at which the ankle is held during the procedure. Similarly, if the need to convert to invasive distraction techniques arises, the system should provide the capability of rapidly converting to an invasive method which provides the amount of distraction needed and allows the ankle to be placed and held in an optimum position for the required surgical technique. In addition, regardless of which technique or method is utilized, the system should be flexible enough to allow repositioning of the limb and the joint during the surgical procedure to provide optimum access to all of the available surgical entrant sites.